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Ashwagandha

Also known as: Withania somnifera, Indian ginseng, Winter cherry

An adaptogenic herb from Ayurvedic medicine, best known for reducing stress and supporting sleep.

Ashwagandha roots, leaves, and ground root powder on natural paper
Editorial illustration

Ashwagandha extracts show a moderate short-term signal for stress and anxiety, with more limited evidence for sleep and exercise outcomes. Trials are small and formulation-specific, and pregnancy avoidance, thyroid effects, sedation, interactions, and rare liver injury deserve attention.1, 3

  • Adaptogenic herb from Ayurveda; root is the part used1, 3
  • Active markers: withanolides1, 3
  • Common studied doses: 300–600 mg of root extract daily1, 3
  • Best evidence: stress, anxiety, and sleep quality1, 3

What is Ashwagandha?

Ashwagandha — Sanskrit for 'smell of the horse,' a nod to the root's aroma and its reputed strength-giving properties — is one of the most-studied herbs in Ayurveda and one of the fastest-growing supplements in the US market. It belongs to the adaptogen family, botanicals said to help the body resist physical and mental stress. The modern evidence base centers on standardized root extracts (often KSM-66 or Sensoril, standardized to withanolides) studied for stress, anxiety, sleep, and, to a lesser extent, physical performance.1

Where it comes from

Natural sources

  • Root of Withania somnifera, native to India, the Middle East, and parts of Africa
  • Traditionally used as powder mixed with milk or honey
  • Leaves are also used in some preparations

How it's made

Supplemental extracts are concentrated and standardized to withanolide content via water or ethanol extraction.

What it does in products

  • Modulation of the hypothalamic-pituitary-adrenal (HPA) stress axis
  • GABA-mimetic-like calming effects (mechanism under study)
  • Cortisol reduction in some trials
  • Traditional use: vitality, sleep, and general wellness

Benefits

Stress and anxiety reduction

moderate evidence

Multiple randomized trials report moderate reductions in perceived stress and anxiety scores with 300–600 mg daily over 8–12 weeks, supported by meta-analyses showing medium effect sizes.3, 2, 1

Meta-analysis finds a stress and anxiety signal, but trials are small, short, use different extracts, and often have industry involvement.

Sleep quality

limited evidence

Trials in people with insomnia symptoms found ashwagandha improved sleep onset and quality, with effects growing over 6–10 weeks; several studies measured lower cortisol.1, 3

Some trials report sleep improvements, usually as a secondary outcome or in stressed participants; extract and dose vary.

Physical performance and strength

limited evidence

Some small trials in resistance-trained adults report modest gains in strength and recovery with 300–600 mg twice daily, though the evidence is less consistent than for stress.1

Small exercise studies report possible strength or recovery changes, but the evidence is not as mature as the stress literature.

Testosterone and fertility support

insufficient evidence

Small studies in selected men have reported hormonal or fertility changes, but they do not establish a testosterone or fertility benefit for the general population.1

Population, baseline fertility status, extract, and commercial sponsorship sharply limit generalization.

Evidence scope and limitations

The review covers standardized oral ashwagandha extracts studied for stress, sleep, exercise, and selected reproductive outcomes; traditional use is not treated as clinical proof.

  • Commercial extracts are not chemically interchangeable and many trials are small or industry funded.
  • Rare liver injury, thyroid effects, pregnancy avoidance, sedation, and drug interactions matter more than the herb's generally mild short-term trial profile.

Evidence last checked: 2026-09-26

Side effects & safety

Drowsiness (uncommon)Take it in the evening if this occurs.
Digestive upset (uncommon)Nausea or loose stools, usually transient.
Liver enzyme elevation (rare)Rare case reports exist; discontinue and see a doctor if you develop jaundice, dark urine, or persistent fatigue.

Safety considerations

  • Ashwagandha is traditionally considered unsafe in pregnancy (potential to stimulate uterine activity) and should be avoided. Its safety in breastfeeding is not established.
  • May amplify the effects of sedatives and sleep medications.
  • Can affect thyroid hormone levels — monitor if you have thyroid disease or take thyroid medication.
  • May modulate immune activity; caution with immunosuppressants.
  • Not for: Pregnancy and breastfeeding
  • Not for: Autoimmune conditions (rheumatoid arthritis, lupus, MS) — use only under supervision
  • Not for: Planned surgery (stop two weeks prior, given its sedative and potential blood-sugar effects)
1

Amounts studied & product use

These figures describe research or common product use, not a personal dose or treatment recommendation.

In supplement studies and products

Stress and sleep trials commonly study standardized extracts in the approximate range of 240–600 mg daily for 6–12 weeks. Extract part, withanolide specification, and manufacturing differ, so milligrams of one product cannot be mapped directly to another.

1, 3

Regulatory status

  • Dietary supplement under DSHEA; no FDA-approved medical use. Manufacturers are responsible for safety and accurate labeling.
4

What 'adaptogen' actually means

Adaptogens are herbs claimed to increase the body's nonspecific resistance to stress. The research framework centers on the HPA axis — the brain-adrenal loop that drives cortisol release. In some ashwagandha trials, morning cortisol levels dropped measurably, and stress questionnaires improved. That said, 'adaptogen' is a traditional and marketing category rather than a regulatory or strictly scientific one; individual products vary in standardization and evidence.

1

Frequently asked questions

How long does ashwagandha take to work?

It is not an acute anti-anxiety medication — benefits accrue over weeks. Most trials show meaningful changes at 6–12 weeks of daily use; some people notice better sleep within the first couple of weeks.1, 3

When is the best time to take ashwagandha?

If your goal is sleep, take it in the evening. For daytime stress, split the dose morning and evening. If it makes you drowsy, shift the entire dose to bedtime.1, 3

Who should not take ashwagandha?

Pregnant or breastfeeding women, people with autoimmune disease or thyroid disorders (unless supervised), those on sedatives, immunosuppressants, or thyroid medication, and anyone scheduled for surgery. As with any botanical, check with your doctor first.1, 3

The bottom line

Ashwagandha is promising for short-term stress outcomes, not a proven all-purpose adaptogen. Extract identity and safety context should drive the decision.

References

  1. Ashwagandha. National Center for Complementary and Integrative Health (2025) · government guidance
  2. An investigation into the stress-relieving and pharmacological actions of an ashwagandha extract. Medicine (2019) · randomized trial · PMCID PMC6750292
  3. Ashwagandha supplementation for anxiety and stress: a systematic review and meta-analysis of randomized trials. Phytotherapy Research (2022) · meta analysis · PMID 36017529
  4. Dietary Supplements. U.S. Food and Drug Administration (2025) · government guidance

Revision history

  1. Replaced search-result citations with exact sources, mapped claims to evidence, and reassessed evidence strength.